• Helping you upgrade your CG career

    Maya error when saving Binary MB file as Ascii MA

    I am trying to save some maya binary scene (.mb) as ascii (.ma) files, but unable to do so - the following
    error dialog pops up every time :

    File contains unknown nodes or data. To preserve this information, the current file type cannot be changed.

    Am not sure what it means by unknown nodes. I have not used any plugins or stuff other than what comes with Maya.
    I did try experimenting with a couple of free Maya plugins earlier, but I had already deleted those objects from my files.

    Any ideas how to solve this error to convert .mb file to .ma ?

    asked 4 Years ago by
    Avatar image of CG Helpline user prismatic

    CGH Score : 11
    Add a Comment for this question
    Please Login or Register to add comment
    1 Answers :

    Since the error says that the file contains unknown nodes, it means at some point of time after this file was created, atleast one node has been added to this file which was most probably by an external plugin. Sometimes, even if you delete objects which are visible in the viewport, you might unknowingly leave behind some associated nodes. These nodes behave well as long as the plugin in question is registered and available, but as soon as you delete the plugin, the same nodes become unknown nodes. There are 2 ways to save a erroring binary .mb file as an ascii .ma file :

    Solution 1 - By Preserving the unknown nodes Open a new tab (python) in the script editor and type the following command :


    Now try to save your file as an ascii, and you will succeed.

    Solution 2 - By Deleting the unknown nodes : You can delete unknown nodes in 2 ways, 1) by using Optimize Scene Size Options and 2) Using a simple script.
    1) Using Optimize Scene Size Options :

    Click the Options button in File/Optimize Scene Size. Scroll down to the bottom of the window that opens up. Tick the check box Remove Unknown nodes, and then click the small "Optimize Now" button next to it. This works most of the time, but sometimes you may find that some of the unknown nodes are locked, in which case optimizer fails to delete it. If you are still unable to save your file as ascii, then use the script method that I've written in the solution (2) below

    2) A python script to delete unknown nodes ( including locked nodes) :

    import maya.cmds as cmds
    unknownNodes = cmds.ls(type="unknown")
    for nd in unknownNodes:
        print "Unlocking ", nd
        cmds.lockNode( nd, lock=False )
        print "Deleting ", nd

    Hope that helps ....

    answered 4 Years ago by
    Avatar image of CG Helpline user aaachooo

    Cambridge, United Kingdom
    CGH Score : 142
    Expertise : Maya; Python; Maxscript;
    Add a Comment for this answer
    Please Login or Register to add comment

    Submit your Answer :


    Page rendered in 0.1212 seconds. Memory usage : 3.96MB.